[RFC PATCH v2 1/5] virtio-balloon: Add Working Set Reporting feature

[T.J. Alumbaugh]

Balloon header includes:
 - feature bit for Working Set Reporting
 - number of Working Set bins member in balloon config
 - types for communicating Working Set information

Signed-off-by: T.J. Alumbaugh <talumbau@google.com>
---
 .../standard-headers/linux/virtio_balloon.h   | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/standard-headers/linux/virtio_balloon.h 
b/include/standard-headers/linux/virtio_balloon.h
index f343bfefd8..df61eaceee 100644
--- a/include/standard-headers/linux/virtio_balloon.h
+++ b/include/standard-headers/linux/virtio_balloon.h
@@ -37,6 +37,7 @@
 #define VIRTIO_BALLOON_F_FREE_PAGE_HINT        3 /* VQ to report free pages */
 #define VIRTIO_BALLOON_F_PAGE_POISON   4 /* Guest is using page poisoning */
 #define VIRTIO_BALLOON_F_REPORTING     5 /* Page reporting virtqueue */
+#define VIRTIO_BALLOON_F_WS_REPORTING  6 /* Working set report virtqueues */
 
 /* Size of a PFN in the balloon interface. */
 #define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -59,6 +60,9 @@ struct virtio_balloon_config {
        };
        /* Stores PAGE_POISON if page poisoning is in use */
        uint32_t poison_val;
+       /* Stores the number of histogram bins if WS reporting in use */
+       uint8_t working_set_num_bins;
+       uint8_t padding[3];
 };
 
 #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
@@ -116,4 +120,20 @@ struct virtio_balloon_stat {
        __virtio64 val;
 } QEMU_PACKED;
 
+enum virtio_balloon_working_set_op {
+    VIRTIO_BALLOON_WS_REQUEST = 1, /* a Working Set request from the host */
+    VIRTIO_BALLOON_WS_CONFIG = 2,  /* a Working Set config from the host */
+};
+
+struct virtio_balloon_working_set {
+       /* A tag for additional metadata */
+       __virtio16 tag;
+       /* The NUMA node for this report. */
+       __virtio16 node_id;
+       uint8_t reserved[4];
+       __virtio64 idle_age_ms;
+       /* A bin each for anonymous and file-backed memory. */
+       __virtio64 memory_size_bytes[2];
+} QEMU_PACKED;
+
 #endif /* _LINUX_VIRTIO_BALLOON_H */
-- 
2.41.0.rc0.172.g3f132b7071-goog